Drafting machine of the guide-wire type



Jan. 16, 1962 D. G. FALCONER 3,016,614

DRAFTING MACHINE OF THE GUIDE-WIRE TYPE Filed on. 18, 1957 2Sheets-Sheet 1 7 Dawn 6. l LcozvEe INVENTOR.

1962 D. G. FALCONER 3,016,614

DRAFTING MACHINE OF THE GUIDE-WIRE TYPE Filed Oct. 18, 1957 2Sheets-Sheet 2 66 w 56 F2? 'DlqU/D 6. 62 V 68 h BY WW? I j 7' StatesDavid G. Falconer, Washington, D.C., assignor to .lonlren FriendCorporation, a corporation of Delaware Filed Get. 18, 1957, Ser. No.691,093 1 Claim. (Cl. 33--8tl) This invention has for its aim theprovision of an improved form of drafting machine, for use in connectionwith the usual form of flat or inclined drafting table, to enable thefull range of drawing or design operations to be accomplishedefficiently and without disadvantages encountered in the use ofpreviously known machines of this type.

In particular, the invention permits the employment of a straight mainor reference support element which will support the actual pencil or penguiding straight-edge or protractor element, hereinafter called thedrafting instrument, in such a Way that the latter can easily bemaintained in a set position, or equally well be moved to a differentposition, strictly parallel to itself, in any desired direction over thetable surface. The main or reference support is itself in the form of ashaft, whose opposite ends are guided by taut wires in such a way thatthe support is maintained accurately parallel to one edge of the tableor board regardless of how it may be moved parallel to itself to placethe other parts in desired locations. The invention also providesrelated features which permit the parts to be moved as desired withoutsmudging or touching the work being done, without hindrance from smallarticles lying on the working surface, and under continuous control ofthe operator.

The invention further provides, for use with a reference support of thekind described, an improved form of connection whereby the protractor orstraight-edge drafting instrument will be guided by the referencesupport to the desired working position, but so arranged that theprotractor or drafting device or instrument can easily be slightlytilted up from the Working plane (-to clear the work), or even liftedentirely free from the main support shaft for immediate replacement by adifierent type of drafting instrument. This feature is obtained withoutany sacrifice of the accurate geometric relation of the parts in use.The same arrangement provides a convenient support for one hand or theforearm of the draftsman, and by which the drafting instrument such as astraight-edge guide or protractor can be tilted away from the work,moved as desired from place to place, or held firmly in the workingposition. Other advantages of the invention will become apparent fromthe following description.

Reference is now made to the accompanying drawings forming a part ofthis disclosure, and in which:

FIGURE 1 is a perspective view of the essential parts of one preferredembodiment of the invention.

FIGURE 2 is a fragmentary sectional view taken along linen 2-2 of FIGURE1.

FIGURE 3 is a similar sectional view taken on line 3--3 of FIG. 1.

FIGURE 4 is a partial plan view of the essential features of a modifiedform of the invention.

FIGURE 5 is a sectional view taken on line 5-5 of FIGURE 4.

FIGURE 6 is a diagrammatic illustration of a modified way of winding theguide wires for the main support shaft.

FIGURE 7 is a view similar to FIG. 1 of a slightly modified form of theinvention, and illustrating a form of parallel ruler for use with any ofthe various forms.

FIGURE 8 is a sectional view taken on line 3--8 of FIGURE 7.

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Referring first to FIGURES 1 to 3 of the drawings, the invention isillustrated as applied to the usual board, table top or like draftingsurface designated reference numeral 10. Rolling along two oppositemarginal edges of the board 10 are cylindrical hubs 12, 14 which arefast on the opposite ends of the main reference element shown as shaftI6 of cylindrical form. Upper and lower guide wires 18, 20 of flexiblebut substantially inextensible cord or wire, are secured at theiropposite ends to the board corners as at screws 22.. Each wire iswrapped at least once about the periphery of the corresponding hub,which may thus roll along the wire surface with the wire in turn lyingupon the board surface. Adequate friction between wire and hub isensured by the tensioning springs 24, 26, but tensioning weights mayobviously be submitted if desired.

Since the shaft 16 is of smaller diameter than the hubs, the shaft iskept out of contact with the board and in fact can clear small objectslying on the working surface. The arrangement described requires nooverhanging parts, so that the board or table may be placed directlyagainst walls or others furniture Without interference. If desired, eachhub may be provided with a flange, as at 28, engaging the side margin ofthe board 10, to minimize end play if such is objectionable for the workin hand.

The pencil-guiding drafting instrument or protractor is indicated as awhole by reference numeral 30, and may take any desired form. However,its manner of connection to the shaft support 16 is desirably such as toensure its positional rigidity without hindering its movement whendesired, or complete removal if that is wanted. Thus, the connectionpreferably takes the form of a bracket 32 which rests upon the shaft 16with a wedging action due to its own weight or the hand or forearm ofthe operator upon the upper surface of the bracket. As best shown inFIGURE 3, the actual bearing surface between the bracket and shaft maybe provided by protuberances 34 on the inclined sides of the former,which slide along the shaft, and these may incorporate inherent frictionsufficient to minimize accidental shifts, as when the board is tilted.FIGURE 3 indicates in dash lines the way in which such a bracket can betilted by the operator, as merely by a sliding force exerted on thebracket top surface, to clear the work itself and prevent any smudging.Obviously, also, the entire unit of bracket and protractor can be liftedfree when desired. The cantilever arrangement relative to shaft 16permits the desired tilting action of the drafting instrument.

For use when long lines are to be drawn parallel to a long edge of theboard or table, a collar 36 may be positioned on the shaft 16 and lockedin place as by a setscrew 38 preferably forcing a nylon or like clampelement against the shaft 16. The collar size will of course be lessthan the diameter of the hubs 12, 14 so that the collar will clear theworking surface.

In the simplified form shown in FIGURES 4 and 5 of the drawings, thehubs are omitted, and the wires make several turns about the mere endsof shaft 16. In this case, of course, less clearance will be providedfor articles lying on the working surface of the board. It is to beunderstood that the same drafting appliances as described above may beused with the form shown in FIGURES 4 and 5. To avoid the necessity forexcessive frictional contact tension, the wires may be anchored to theshaft ends in the manner indicated in FIGURE 5, by a clamp screw 40engaging a central part of the wire 18, which makes several turns aboutthe shaft 16 before extending to the table edges. It is important thatin this form, as well as in all the other forms of the invention, onlyrolling contact elements lie between the shaft and the work surface; norubbing contact is involved.

A differentformof windingarrangement for the wires 18 and 20 is shown inFIGURE 6, in which each wire is actually formed in two independentpieces designated 42 and: 46. Each piece is separately anchoredto theshaft 1 6. as by having1its end secured in a hole in the shaft, and thewires are then wrapped in opposite senses about the' shaft so that thedistance 48 will remain constant as the shaft rolls along thetable.

ln the embodiments described above, the guide wires lie on the table orboard, or at least within its outer periphery. It is also possible toarrange the wires entirely outside the periphery, as by the form shownin FIGURE 7. Here, edge brackets .56 have the wire ends anchored tothem, so that the wires are outside the boards edge and preferablyslightly below its top surface. It will be seen that this involves a hubdiameter greater than as described above, and to avoid any sliding,slippage or the like due-to the difference in peripheral speed asbetween the hub and the shaft, sleeves 52 and 54 loosely receiving theshaft 16 are arranged to roll along the board surface in the desiredmanner and regardless of the'diameters of the hubs.

FIGURE 7 also illustrates a particularly advantageous embodiment of thearrangement carried by shaft is. Here, a simple stirrup element 56 ishooked over the shaft 16,v and between the shaft-engaging half loops 53and 6d the shaft carries the bracket of a straight-edge or protractorunit 62. The fiducial edge of the stirrup element is indicated at 64 inFIG. 8, and the elements e and 62 can be swung about the shaft asindicated, to clear the work surface. An abutment so on the protractoris preferably arranged to engage a strip 68 on the stirrup element 56when the protractor is tilted, so that the straight edge part 64 of thestirrup is automatically raised clear at the same time. The stirrup halfloops lie inside sleeves 52 and 54- and straight edge 64 is thus nearlyas long as the table width, to permit short or long parallel verticallines to be drawn accurately.

Having described several preferred forms of the ini vention, it is to beunderstood that the principles of the invention can be effectuated byother specific arrangements, and that all such are included in the scopeof this invention as fall Within the true spirit and meaning of theappended claim. In the claim, reference to the shaft itself is to betaken as including any parts, such as hubs, which are or may befunctionally integral therewith so as to turn with the shaft, unless thecontextindicates that such an interpretation is not intended.

What is claimed is:

In a drafting machine or the like, in combination, a support shaftmountedfor free movement always parallel to itself along and above aworking surface, a bracket having inclined side Walls encompassing theshaft and having bearing elements disposed to contact the shaft wherebyto locate the bracket for sliding motion lengthwise of the shaft, adrafting instrument carried by saidbracket and extending outwardly alongand above said surface to one side only of said shaft, to permit tiltingmotion of the bracket about the shaft as an axis andthereby to lift thedrafting instrument away from the working surface; a straight-edgeelement having stirrup portions partly encirclingsaid shaft fortiltingmovements of said straight-edge elemennand cooperating abutmentson said drafting instrument bracket and said straightedge element, totilt the latter element upon tilting movements of the bracket.

References Cited in the file of thispatent UNITED STATES PATENTS

